Why does a recipe call for garlic powder over fresh garlic?

Could be any number of reasons. Maybe the chef prefers garlic powder, maybe the recipe is designed to be easy and quick (and powder is faster than mincing) or maybe it's a texture -- the recipe should yield something smooth not something with chunks in it. For example, I use garlic and onion powders in my mac and cheese recipe because chunks of onion and garlic don't give with how I expect mac and cheese to be.